Star anise essential oil recovery by hydrodistillation with ultrasonic pretreatment and evaluation of physicochemical properties

This study investigates essential oil recovery from Lang Son star anise fruits (Illicium verum Hook. f.) using hydrodistillation with ultrasonic pretreatment and evaluates selected physicochemical properties of the resulting oil. Finely ground material was mixed with water at a ratio of 1:9 (g/mL) and subjected to probe ultrasonication for 30 minutes at temperatures below 37°C using amplitudes of 30%, 40%, and 50%, followed by 90 minutes of hydrodistillation. The corresponding essential oil yields were 6.83%, 4.22%, and 3.62% (v/w), respectively. Among the investigated conditions, the 30% amplitude produced the highest recovery yield. The analyzed essential oil had a reported relative density of 0.980 at a measurement temperature of 23.4°C and an acid value of 1.71 mg KOH/g. The findings provide information on essential oil recovery and selected physicochemical characteristics for evaluating laboratory-scale extraction conditions.